BEIRUT — Issuing Tehran’s strongest warning to date, a top Iranian official said Saturday that any attack on Syria would be deemed an attack on Iran, a sign that it will do all it can to protect embattled Syrian President Bashar Assad.

Ali Akbar Velayati, an aide to Iran’s supreme leader Ayatollah Ali Khamenei, made his comments as Syrian troops conducted offensive air raids against rebels and discovered a trio of tunnels they were using to smuggle weapons in their fight to topple Assad.

The world has been grappling over how to deal with Syria ever since an uprising against Assad’s regime erupted nearly two years ago. But so far, there has been no international intervention on the ground where more than 60,000 people have been killed, according to the United Nations.

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Iran is Syria’s strongest ally in the Middle East, and has provided Assad’s government with military and political backing for years. In September, the top commander of Iran’s powerful Revolutionary Guard, General Mohammad Ali Jafari, said the elite unit had high-level advisers in Syria. Iran also is believed to be sending weapons and money to Syria as it endures its worst crisis in decades.

‘‘Syria plays a very key role in supporting or, God forbid, destabilizing the resistance front,’’ Velayati was quoted by Iran’s semiofficial Mehr news agency as saying. ‘‘For this same reason, [an] attack on Syria is considered [an] attack on Iran and Iran’s allies.’’

By backing the rebels trying to oust the Syrian leader, the US and Arab states in the Gulf attacked the ‘‘golden ring of resistance,’’ Valayati said, referring to the militant groups, Hamas and Hezbollah, and Iran and Syria, which are all anti-American.

Iran also is at odds with the international community over its nuclear program, although Iran insists it is using the program solely for peaceful purposes, not nuclear weapons.

A former Iranian diplomat who defected to the West in 2010 told Israel’s channel 2 TV in an interview broadcast on Friday that if Tehran acquired nuclear weapons, it would use them against Israel.

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Mohammad Reza Heydari, who has political asylum in Norway, said Venezuela was flying uranium and various components for nuclear weapons to Tehran. Venezuela backs Iran in arguing the nuclear program is purely for peaceful purposes.

Since the unrest in Syria began in March 2011, opposition forces have taken control of wide swathes of territory, mostly in the north near Syria’s border with Turkey.

NATO said Saturday that the first of six Patriot missile batteries being deployed to Turkey to shoot down missiles that might come from the Syrian side of the border was now operational.

The battery, meant to protect the Turkish city of Adana, was provided by the Netherlands.

The United States, Germany, and the Netherlands are providing two batteries each of the latest version of the US-made Patriots. The other five Patriot batteries are expected to be operational in the coming days in Adana, Kahramanmaras, and Gaziantep.

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NATO says the Patriots would be used for defensive purposes only. Syria has not fired any of its surface-to-surface missiles at Turkey during the civil war, but the Assad regime has described the NATO deployment as a provocation.

The alliance also deployed Patriot batteries to Turkey during the US-led invasion of Iraq 10 years ago. They were never used and were withdrawn a few months later.

Turkish Prime Minister Recep Tayyip Erdogan, interviewed on Turkish television late Friday, said the Syrian opposition now controls some 70 percent of Syria. ‘‘Bashar is walking, propped up from behind,’’ said Erdogan, a close ally of Assad’s until the crisis began.

In fighting on Saturday, Syrian forces clashing with rebels said they uncovered tunnels used to smuggle weapons and move around Daraya, a suburb of Damascus, state media said.